package org.bouncycastle.asn1;

import java.io.IOException;

/**
 * DER NumericString object - this is an ascii string of characters
 * {0,1,2,3,4,5,6,7,8,9, }.
 */
public class DERNumericString extends ASN1Object implements DERString {
    String string;

    /**
     * return a Numeric string from the passed in object
     * 
     * @exception IllegalArgumentException
     *                if the object cannot be converted.
     */
    public static DERNumericString getInstance(Object obj) {
        if (obj == null || obj instanceof DERNumericString) {
            return (DERNumericString) obj;
        }

        throw new IllegalArgumentException("illegal object in getInstance: "
                + obj.getClass().getName());
    }

    /**
     * return an Numeric String from a tagged object.
     * 
     * @param obj
     *            the tagged object holding the object we want
     * @param explicit
     *            true if the object is meant to be explicitly tagged false
     *            otherwise.
     * @exception IllegalArgumentException
     *                if the tagged object cannot be converted.
     */
    public static DERNumericString getInstance(ASN1TaggedObject obj,
            boolean explicit) {
        DERObject o = obj.getObject();

        if (explicit || o instanceof DERNumericString) {
            return getInstance(o);
        } else {
            return new DERNumericString(ASN1OctetString.getInstance(o)
                    .getOctets());
        }
    }

    /**
     * basic constructor - with bytes.
     */
    public DERNumericString(byte[] string) {
        char[] cs = new char[string.length];

        for (int i = 0; i != cs.length; i++) {
            cs[i] = (char) (string[i] & 0xff);
        }

        this.string = new String(cs);
    }

    /**
     * basic constructor - without validation..
     */
    public DERNumericString(String string) {
        this(string, false);
    }

    /**
     * Constructor with optional validation.
     * 
     * @param string
     *            the base string to wrap.
     * @param validate
     *            whether or not to check the string.
     * @throws IllegalArgumentException
     *             if validate is true and the string contains characters that
     *             should not be in a NumericString.
     */
    public DERNumericString(String string, boolean validate) {
        if (validate && !isNumericString(string)) {
            throw new IllegalArgumentException(
                    "string contains illegal characters");
        }

        this.string = string;
    }

    public String getString() {
        return string;
    }

    public String toString() {
        return string;
    }

    public byte[] getOctets() {
        char[] cs = string.toCharArray();
        byte[] bs = new byte[cs.length];

        for (int i = 0; i != cs.length; i++) {
            bs[i] = (byte) cs[i];
        }

        return bs;
    }

    void encode(DEROutputStream out) throws IOException {
        out.writeEncoded(NUMERIC_STRING, this.getOctets());
    }

    public int hashCode() {
        return this.getString().hashCode();
    }

    boolean asn1Equals(DERObject o) {
        if (!(o instanceof DERNumericString)) {
            return false;
        }

        DERNumericString s = (DERNumericString) o;

        return this.getString().equals(s.getString());
    }

    /**
     * Return true if the string can be represented as a NumericString
     * ('0'..'9', ' ')
     * 
     * @param str
     *            string to validate.
     * @return true if numeric, fale otherwise.
     */
    public static boolean isNumericString(String str) {
        for (int i = str.length() - 1; i >= 0; i--) {
            char ch = str.charAt(i);

            if (ch > 0x007f) {
                return false;
            }

            if (('0' <= ch && ch <= '9') || ch == ' ') {
                continue;
            }

            return false;
        }

        return true;
    }
}
